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The present invention relates to cryosurgical tissue ablation, and in particular, to a device and method which increases the effective freezing length in the device tip while simultaneously maintaining a usable device size and safe operating characteristics.
Advances in medical procedures have resulted in the development of procedures which use minimally invasive surgical techniques such that one or more slender implements such as probes or catheters are inserted through one or more small incisions into a patent""s body. These implements include surgical ablation implements having a rigid or flexible structure in which the ablation device is located at or near the implement""s distal end that is placed adjacent to the tissue to be ablated.
Radio frequency energy, microwave energy, laser energy, extreme heat and extreme cold can be provided by the ablation device to kill the tissue. Certain procedures, such as cardiac procedures, are performed by selectively ablating the tissue. For example, in the case of a cardiac arrhythmia, the cardiac tissue is selectively ablated to eliminate the source of the arrhythmia. A popular minimally invasive procedure using radio frequency (RF) catheter ablation, has been used as has cryoablation in which the RF and cryogenic devices are arranged to provide very limited spot-sized lesions. As such, these conventional devices are not well suited for tissue ablation along a length, i.e. larger than a spot-sized lesion.
In order to achieve freezing ablation along a length using conventional devices, a series of spot ablation lesions are created by moving the device tip located at the distal end of the device along the length to be ablated. The device typically includes a single cryogenic fluid lumen. Use of this arrangement can be time consuming, thereby prolonging procedure duration, and can result in an uneven ablation, reducing the effectiveness of the procedure. It would therefore be desirable to have a cryosurgical device that provides enhanced cooling capability for spot lesions, as well as the capability to create other than spot lesions.
The present invention provides a device that provides enhanced cooling capability for spot lesions and the capability to create other than spot lesions, as well as a method for ablating tissue. In an exemplary embodiment the device includes a tip having a thermally transmissive region along a length thereof. The thermally transmissive region is operable at a temperature sufficient to cryosurgically ablate tissue in contact therewith. Fluid injection lumens are positioned within device so that the ends of the lumens are at different points along the length of the thermally transmissive region. Each of the ends are arranged to cool overlapping portions along the length of the thermally transmissive region when cryogenic fluid is ejected from the the fluid injection lumens.
In an exemplary method for cryosurgically ablating tissue, a cryosurgical tip is positioned at tissue to be ablated, the tip having a thermally transmissive region along a length thereof. Cryogenic fluid is sequentially injected into the tip through multiple cryogenic fluid injection lumens terminating within the tip at different points along the length of the thermally transmissive region.